Food Allergy in South Africa.

PURPOSE OF THE REVIEW

Whilst food allergy seems to have increased significantly in many developed countries in the past few decades, quality data on the burden of food allergy in many developing countries is scanty. Until recently, South Africa had a dearth of robustly designed food allergy studies. This article summarizes some of the recent research and observations regarding food allergy from the South African setting.

RECENT FINDINGS

South Africa has recently seen two important food allergy prevalence studies in selected and unselected populations. Both show allergy rates in keeping with those in several westernized countries. The major difference between sensitization and allergy rates in these studies emphasizes the vital role of the food challenge in differentiating true food allergy from asymptomatic sensitisation in equivocal cases. Eczema, young age and living in an urban population are important risk factors for food allergy in South Africa. Egg and peanut allergy are the most common food allergies in both selected and unselected populations in South Africa. In peanut allergy, Ara h 2 is the most useful component in differentiating true allergy from tolerance in peanut-sensitized patients. Use of internationally derived 95% positive predictive values for peanut and egg allergy produced many false positives in South African studies. Studies in South Africa show a trend towards more conservative introduction of peanut in eczema patients, which needs to be addressed in the light of recent studies showing a protective effect of earlier introduction of peanut. "Novel" allergies such as galactose-alpha-1,3-galactose allergy, food protein-induced enterocolitis syndrome and eosinophilic oesophagitis are being described with increasing frequency in South Africa. The surprisingly high prevalence of food allergy in South Africa points towards possible involvement of South Africa in the so-called "food allergy epidemic". This has major implications on the planning of health services in the allergy sector. Food challenges will form a vital role in allergy services. Ninety-five percent positive predictive values for peanut and egg allergy may need revision to be more applicable to the local population.